Which muscle lowers and rotates the head?

The muscle responsible for lowering and rotating the head is the sternocleidomastoideus. This muscle is located in the neck and has two points of origin: the sternum and the clavicle, which converge to insert on the mastoid process of the temporal bone of the skull. When either side of the sternocleidomastoideus contracts, it can tilt the head to the same side while rotating it to the opposite side. When both sides contract simultaneously, the muscle can flex the neck and lower the head.

Other muscles listed do not perform this action. The frontalis muscle primarily raises the eyebrows and wrinkles the forehead, while the orbicularis oculi is responsible for closing the eyelids. The temporalis muscle plays a role in mastication (chewing) and helps elevate the jaw but is not involved in head movement. Thus, the function and anatomical placement of the sternocleidomastoideus distinctly align with the action of lowering and rotating the head.